The present invention relates to spatial compounding. In particular, the present invention relates to compounding component frames of data associated with different angles to reduce speckle and produce a more continuous border in specular targets, such as muscle layers.
One component frame of data is acquired by scanning along scan lines at one angle or pattern relative to a transducer. A second component frame of data is acquired by scanning along scan lines at a different angle or pattern. Each of the frames of data represents a different but overlapping region of a patient due to the angle or pattern of the scan lines. The frames of data are compounded together and displayed as an image. The transducer is held at substantially one position on the patient for acquiring the sequential component frames of data.
Steered spatial compounding may mask or change the appearance of clinical markers. Clinical markers are an important diagnostic tool. Either shadows (i.e. dark lines) or a brightened area (i.e. bright lines) are produced in the images of surrounding tissue by objects or obstructions in the body. Calcifications produce shadows. Fluid filled cysts often produce brightened areas. The markers are frequently used to help identify pathology. The appearance and orientation of these markers depends on the orientation of the ultrasound beams. As a result, compounding frames of data associated with different steering angles or patterns reduces or eliminates desirable markers in the resulting compound image.
U.S. Pat. No. 6,858,010 discloses steered spatial compounding where clinical marker information is preserved. For example, an image responsive to less spatial compounding more likely preserves clinical markers than a steered compound image. By displaying both images, clinical markers are identified by the user from one image and other diagnostic information is obtained from the steered compound image. As another example, clinical marker information is added back into or highlighted on a steered compound image for identification by the user. However, movement of the transducer during acquisition of the component frames of data or frames used for identifying clinical markers may result in misalignment of information.
U.S. Pat. No. 6,858,010 discloses that motion between component frames of data may be detected. The component frames of data are then interpolated or altered to compensate for the motion. The motion compensated component frames of data are then used for compounding and identifying markers. However, this in-plane tracking and compensation may be computationally expensive. Out-of-plane motion cannot be corrected by motion tracking and compensation without more complex equipment and computation expense.